This image is part of a series that was created for an open textbook, Aerodynamics and Aircraft Performance. The textbook is available here.
Kindred Grey (2021). "NACA 2412 Airfoil Data." CC BY 4.0. Adapted from NACA. Public domain.
(a) Lift curve slopes are shown for Reynolds numbers of 3.1, 5.7, and 8.9 times 10 to the 6. The curves are linear between angles of attack, alpha knot, of negative 14 and 14 degrees, with stall resulting in curves back towards 0 past these values and a y-intercept of 0.2. The lower end of the lines stop within the linear portion for all but the 5.7 times 10 ^6 case. A final case at 5.7 times 10^6 is shown with standard roughness, which follows the same linear path until alpha knot of 8, after which is begins to turn back down. Moment coefficient c sub m c over 4 is approximately negative 0.2 within the linear portion, growing more positive at the negative stall angles, and more negative at the positive stall angles.
(b) Section drag coefficient, c sub d, is shown as a function of section lift coefficient, c sub l. The curves follow the same parabolic shapes as before, centered now at c sub l of 0.2 and c sub d of 0.006. The standard roughness curve is shifted up to a c sub d of 0.010. The moment coefficients are all approximately negative 0.5 for all Reynolds numbers.